/*
 *  Copyright 2016 Google Inc. All Rights Reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package com.google.android.apps.forscience.javalib;

public abstract class Refresher {
  private final Scheduler scheduler;

  private boolean refreshScheduled = false;
  private Runnable refreshRunnable =
      new Runnable() {
        @Override
        public void run() {
          refreshScheduled = false;
          refresh();
        }
      };
  private Delay delay;

  public Refresher(Scheduler scheduler, Delay delay) {
    this.scheduler = scheduler;
    this.delay = delay;
  }

  public void refresh() {
    final boolean rescheduleWouldBeUseful = doRefresh();
    if (rescheduleWouldBeUseful && !refreshScheduled) {
      refreshScheduled = true;
      scheduler.schedule(delay, refreshRunnable);
    }
  }

  /**
   * Does the scheduler-specific work of refreshing
   *
   * @return true iff another refresh should be scheduled.
   */
  protected abstract boolean doRefresh();
}
